This invention relates to photographic cameras, and more particularly to focal plane shutter units for cameras.
The presently available cameras generally employ an aluminum camera housing formed by die casting. Recently attempts have been made to decrease the weight of a camera by using plastics as a material of the camera housing. Although the plastics are light weight and characterized by good formability which assists in providing complicated articles in a simple forming operation to thereby give a great advantage of reducing the production cost of the camera body, the plastic moldings are very susceptible to shrinkage and deformation resulting from the aging and ambient temperature variation. Consequently, the spatial relationships of the camera parts directly mounted in the plastic housing of the camera are difficult to be stabilized with time. If a change in the dimension between the objective lens and the focal plane accidentally occurs, a decrease in the quality of an image formed on the focal plane will result. For this reason, the employment of plastics in making camera bodies is limited to those designed to be equipped with objective lenses having relatively small relative apertures and short focal lengths.